reference levels

gregit

I guess I'll break down and show just how much of a n00b I am.

Could someone briefly explain "reference levels" and how they apply to setting up a HT system?

Thx

Greg

pjdami

Hi Greg,

You can find a pretty detailed discussion here:

http://clubpolk.polkaudio.com/forum/showthread.php?s=&threadid=14847

I don't mean to be rude by not answering your question directly but there are also plenty of other threads about this topic if you use the search feature.

If you still have questions after doing some reading give us a shout again.

Paul

gregit

Thanks for your reply. Believe me...I tried using the search before I showed my ignorance...so I suppose I'm ignorant on the search function as well ...double whammy!!

pjdami

No problems Greg.

Oh by the way, I noticed you have a Yamaha receiver. Ref level for the Yamaha will not be 00. You will find that you will get 85 db on your surrounds / mains at a bit sooner than that. Its all relative though. Just make a note of what the volume is when you achieve 85 db on your mains and write that down as your reference level. I had a RX-V1300 last year, and recall that it was around -25 db I think (trying hard to remember). You'll see what I'm talking about though once you get started.

Do you have the S&V or Avia DVD?

Paul

gregit

I haven't bought the Yamaha yet. I'm just beginning to put together the system for the new house we'll be moving in May. I have my mains and surround speakers, sent back the PSW505 sub in order to get a SVS (couldn't resist after reading all the good things on the CP forum).

The reason I was asking about reference levels was that in an email from Tom V at SVS he said the following :

" The PB-1isd will be a fine choice…but it wouldn’t be reference level capable in your room. The placement you have picked out should work fine. In that location, you can count on extension down to the 18-20hz range and a clean 112-115dB of output from the PB-1isd with no problem at all. That is very loud bass…but not quote reference level..:)"

To answer your question I don't have either the Avia or S&V discs yet.


Side note:

Just thought this might be interesting: Here it the complete email I received from another sub company in response to the very same inquiry i sent SVS:

"A (insert comparable internet -based competitor's model # here) in the front right corner or as an end table to the right of the sofa would be great (between the sofa and love seat)."

Seems that some companies take their customer service a bit more seriously than others.

Dr. Spec

S&V will work fine for most. Avia is for major tweakers.

Don't buy DVE for sub calibration; it has a level problem with the subwoofer calibration tone. DVE is fine for video.

Reference Level is VERY loud. Most subwoofers are incapable of even approaching RL without puking their guts out, compressing peaks, and lopping off entire octaves.

RL will result in bass peaks in the 115-120 dB region at the seat. After you calibrate your system to RL, you will probably find -15RL to -10RL to be a "comfortably loud" for most DVDs.

Even -10RL takes a hella sub in most rooms: 105-110 dB bass peaks at the seat.

Based on what Tom V is saying, the PB1-ISD should be able to easily handle -15RL to -10RL for most DVDs in your size room at the seating distance you provided. But -10RL would probably be pushing the clean limits of the PB1-ISD.

If you are going to be pushing past -10RL occasionally, the PB2-ISD is a very good idea and will give you the clean headroom you need to hit those peaks without compression or bottoming.

Understanding RL and where you normally listen in relation to RL is extremely important in the sub selection process.

gregit

Thanks for helping put it all into perspective.

Dr. Spec

Straight from the "horses mouth":

Quote:

When trying to decide "how much" subwoofer you need...the last thing anyone shoudl do is base their decision solely on POVs like...." well, I have subwoofer X and it scares my cat and I would be terrified to have more power, and if anyone else does they will be deaf in 6 months". That doesn't work.(and it isn't factual)

What you NEED to do is calibrate your surround system with a SPL meter. Then decide how loud you'll want to crank the system on action oriented DVDs...even if is just demos of the system for 15 minutes at a time. The next step is factoring in how you'll like to have the bass calibrated in the system. Almost all HT enthusiasts like to have the bass 2-3dB hot...MANY like to have it set 5-6dB hot. That is fine...personal preferences and all that...but you must consider that when subwoofer shopping.

For example, with all speakers set to SMALL(which almost always works best)...the subwoofer can be asked to produce 121dB of clean output to all the listening positions in the room. If you have the bass set 6dB hot...then that would up the requirements to 127dB. so even IF you *only* wanted to listen to action oriented DVDs at 10dB under reference(which would be considered moderately loud to most folks)...the subwoofer would still need to have 117dB of headroom.

If your subwoofer isn't capable of that, then your audio presentation will be compromised(often very audibly so)...end of story.

We get many purchase inquires that start out considering a PCi model...but within a few emails they explain that they want to listen to action oriented DVDs in the 6-9dB under reference range(that seems to be the most common range) without worrying about the subwoofer straining. Once I explain the above to them(that this indicates they really need 112-124dB of headroom depending on the bass calibrations) they quickly realize that they may have to reconsider their purchase, or their intended listening levels.

Having slightly more headroom than needed is never a bad thing either...all that means is the subwoofer will be coasting on demanding material. Dynamics stay sharp, distortion stays low and the overall bass quality remains very high regardless of listening levels.

No one wants to over spend...but even worse is buying a new product only to decide you need to upgrade it 3 months later...

Tom V.
SVS

Bill H

Originally posted by pjdami
No problems Greg.

Oh by the way, I noticed you have a Yamaha receiver. Ref level for the Yamaha will not be 00. You will find that you will get 85 db on your surrounds / mains at a bit sooner than that. Its all relative though. Just make a note of what the volume is when you achieve 85 db on your mains and write that down as your reference level. I had a RX-V1300 last year, and recall that it was around -25 db I think (trying hard to remember). You'll see what I'm talking about though once you get started.

Do you have the S&V or Avia DVD?

Paul

Paul, Can you not set all your speaker levels to a -dB setting and set the volume control to 00 and adjust each speaker for 85 dB so 00 is Ref level?

I'm going to buy a Yamaha 1400 and sure would like RL to be 00.

Bill

pjdami

Paul, Can you not set all your speaker levels to a -dB setting and set the volume control to 00 and adjust each speaker for 85 dB so 00 is Ref level?

Bill,

Theoretical one could, I follow you here and thought about that myself. However, the adjustments are very large.

With the 1300 (not sure about the newer model), if one had a great mismatch between the efficiency of the mains and the surrounds (with the mains L & R being much higher in efficiency) one can then turn down the gain level on the mains - 10 db and then there is a feature which allows one to match the sound level up to + 10 db with the surrounds. I decided against making large adjustments like that and I'm thinking that even this would not get you close to where you need to be.

You may want to PM hamzahsh and ask him about the 1400 because he just bought one and is very familiar with its features. Fireshoes might know too; I think he has the 2400.